Between Elemental Match and Mismatch: From K₁₂Ge_3.5Sb₆ to Salts of (Ge₂Sb₂)²⁻, (Ge₄Sb₁₂)⁴⁻, and (Ge₄Sb₁₄)⁴⁻

Abstract

Abstract The solid mixture “K 2 GeSb” was shown to comprise single‐crystalline K 12 Ge 3.5 Sb 6 ( 1 ), a double salt of K 5 [GeSb 3 ] with carbonate‐like [GeSb 3 ] 5− anions, and the metallic Zintl phase K 2 Ge 1.5 . Extraction of 1 with ethane‐1,2‐diamine in the presence of crypt‐222 afforded [K(crypt‐222)] + salts of several novel binary Zintl anions: (Ge 2 Sb 2 ) 2− (in 2 ), (Ge 4 Sb 12 ) 4− (in 3 ), and in the presence of [AuMePPh 3 ] also (Ge 4 Sb 14 ) 4− (in 4 ). The anion in 2 represents a predicted, yet heretofore missing pseudo‐ tetrahedral anion. 4 comprises a cluster analogous to (Ge 4 Bi 14 ) 4− and (Ga 2 Bi 16 ) 4− , and thus one of the most Sb‐rich binary p‐block anions. The unprecedented cluster topology in 3 can be viewed as a defect‐version of the one in 4 upon following a “dead end” of cluster growth. The findings indicate that Ge and Sb atoms are at the border of a well‐matching and a mismatch elemental combination. We discuss the syntheses, the geometric structures, and the electronic structures of the new compounds.